Voluntary Motion

Question 1

• Function of dorsal visual pathway in the production of voluntary motion

Answer 1

• Travel from occipital cortex to parietal/frontal cortex
• enables us to complete motor acts based off of visual input
• Allows us to reach and grasp for objects

Question 2

From the visual cortex, information is sent to what areas in the parietal cortex?

What is the function of each of these areas?

Answer 2

• V6A
• PEc
• MIP
• VIP-creates rough map of space around you

Question 3

• From the VIP, information is sent to _ within the premotor cortex
• This area gives us information about?

Answer 3

• F4
• Creates a detailed map of space around you
• Neurons in F4 are excited by proximity
• F4-surroundings and floor

Question 4

• From the VIP, information can also be sent to _ (which is located in the premotor cortex and perceives where your body is in relation to what is around you)

Answer 4

• F2-where are you

Question 5

• Functions of neurons in the anterior interparietal area and PFG

Answer 5

• Seeing an object to grasp (visually dominant neurons)
• Grasping an object (motor dominant neurons)
• Both seeing and grasping an object (visuomotor neurons)

Question 6

• Neurons from the anterior intraparietal area and PFG relay their information to _ (located rostral to the premotor cortex)
• What is the function of this area?

Answer 6

• F5
• Neurons in F5 fire with GOAL of action, not motor action itself
• F5-with goal in mind

Question 7

• Functions of the premotor cortex

Answer 7

• Receives sensory info required to move (F4 and F5 in particular)
• Applies rules that it is appropriate to move
• Identifies the intent of the motion and decides which motion to produce

Question 8

• What are the two divisions of the supplementary motor cortex
• What are their functions of the subdivisions
• What is the overall function of the supplementary motor cortex

Answer 8

• Supplementary motor area
  
  • Postural control
• Pre-SMA
  
  • Plans motor program required to make action occur
• SMC as a whole
  
  • ​Organize motor sequences
  • Acquire motor skills
  • Executive control (switch actions/alter strategies)

Question 9

• Primary motor cortex functions/characteristics

Answer 9

• Precentral gyrus
• Controls specific movements
• Regions of body that do fine motions have proportionally high representation
• Arranged in columns (more columns in areas of brain that require fine motor movements)

Question 10

If we are in an area that controls a fine motion, stimulation may produce contraction of _

If we are in an area that controls general motion, stimulation may produce contraction of _

Answer 10

• Single muscles
• Group of muscles

Question 11

• What is the input layer of the primary motor cortex?
• What is the output layer of the primary motor cortex? (To which pathway does this travel?)

Answer 11

• Layer IV receives input (muscle and joint proprioceptors amongst others-need to know where we are in space to determine how we will execute a specific movement)
• Layer V-Corticospinal pathway (LMNs)

Question 12

• What are the functions of the two sets of neurons in the primary motor cortex?

Answer 12

• One set of neurons starts the motion
• One set of neurons maintains the motion

Question 13

• Neighboring columns control _

Answer 13

• Related motions

Question 14

• What are the two types of columns

Answer 14

• On/off for agonist muscle
• On/off for antagonist muscle

Question 15

• Role of cerebellum

Answer 15

• Sequence complex actions
• Correct force/direction
• Balance and eye movements
• Learning of complex actions

Question 16

• What are the three functional divisions of the cerebellum

Answer 16

• Vestibulocerebellum
• Spinocerebellum
• Cerebrocerebellum

Question 17

• What are the two areas of the spinocerebellum
• What are the functions of each area

Answer 17

• Vermal and paravermal regions
• Vermal region
  
  • Postural adjustments to ongoing motions
• Paravermal regions
  
  • Correct ongoing motions
  • Control ballistic motions

Question 18

• The vermal region of the spinocerebellum
  
  • Inputs
  • Outputs

Answer 18

• Inputs
  
  • ​Vestibular
  • Visual and auditory
  • Efferent copy (what brain sends to muscle)
• Output
  
  • ​Interpositus n
  • Fastigal n
  • Rubrospinal tract

Question 19

• The paravermal region of the spinocerebellum
  
  • ​Input
  • Output

Answer 19

• Input
  
  • ​Muscle afferent
  • Efferent copy (what brain sends to muscle)
• Output
  
  • ​Interpositus n.
  • Rubrospinal tract

Question 20

• Location and function of the cerebrocerebellum

Answer 20

• Lateral cerebellum
• Plan complex motion
• Sequence of motions

Question 21

• Cerebrocerebellum
• Inputs
• Outputs

Answer 21

• Inputs
  
  • ​All regions of the cerebral cortex
• Outputs
  
  • ​Dentate
  • Back to cortex

Question 22

• Function of the vestibulocerebellum

Answer 22

• Future
• Balance/Eye movements

Question 23

• Vestibulocerebellum
  
  • ​Inputs
  • Outputs

Answer 23

• Inputs
  
  • ​Vestibular afferents (direct or indirect)
• Outputs
  
  • ​Fastigal n. to vestibular nuclei
  • Ascend or descend

Question 24

• What are the deep cerebellar nuclei

Answer 24

• Dentage
• Fastigal
• Interpositus
  
  • Globose
  • Emboliform

Question 25

* ***To produce a motion, what must occur? (Generally speaking)***

Answer 25

* Stimulation of the direct pathway * Inhibition of the indirect pathway

Question 26

* ***What needs to occur to prevent a motion from occuring (Generally speaking)?***

Answer 26

* Inhibit the indirect pathway

Question 27

* How does dopamine affect the direct and indirect pathways? * What type of dopamine receptors are present in each pathway? * End results?

Answer 27

* Dopamine * D1 receptors on direct pathway * Excited by dopamine * ALLOWS motion * D2 receptors on indirect pathway * Inhibited by dopamine * Excited by EAA/ACh * INHIBITS motion

Question 28

* ***D1 and D2 receptors are located in the \_*** * ***Stimulated or inhibited by dopamine released from the \_***

Answer 28

* Striatum * SNPC (Substantia nigra pars compacta)

Question 29

* ***Describe the direct pathway***

Answer 29

* SNPC released dopamine * Activation of D1 receptors on striatum (INFLOW) * Increased release of GABA from the striatum onto cells of the SNPr and GPi (OUTFLOW) * Decreased activity of SNPr and GPi leads to decreased release of GABA from these areas onto the thalamus * Less GABA released onto thalamus, more activity of thalamus * Thalamus releases EAA onto cortex * Allows motion to occur

Question 30

* ***Describe the INACTIVATION OF indirect pathway***

Answer 30

* SNPC releases Dopamine * Dopamine binds D2 receptors on the striatum * Morew GABA released from Striatum onto GPe * GPe more active, and releases less GABA onto the subthalamic nucleus * More activity of subthalamic nucleus * More release of EAA from subthalamic nucleus onto SNPR and GPi * More GABA released from SNPR and GPi onto thalamus * Decreased release of EAA from thalamus to cortex * NO MOTION

Question 31

* Function of basal ganglia * How does it perform its function

Answer 31

* Control beginning (and end of movement) * Inhibiting and withdrawal of inhibition (to prevent and allow movement to occur)

Question 32

* What areas of the brain are important for planning of a complex motor action

Answer 32

* Frontal association area * Supplementary motor cortex * Premotor cortex * Cerebrocerebellum

Question 33

* Interactions between what areas of the brain determine if motion will occur?

Answer 33

* Interactions between frontal, premotor, SMC, and basal ganglia

Question 34

What happens once the appropriate columns in the primary motor cortex are activated?

Answer 34

* APs travel to activate alpha motor neurons of the muscles needed to complete the action * Also activates gamma motor neurons for spindles in the contracting (agonist m) (this is alpha gamma coactivation) * INHIBITS alpha and gamma motor neurons for antagonist m

Question 35

* Once the motion has started, the _ is called upon to make sure the motion is correct

Answer 35

* Spinocerebellum

Question 36

* ***Describe the ACTIVATION of the INDIRECT pathway*** * ***What is the result of activation of the indirect pathway***

Answer 36

* Activation of the indirect pathway leads to NO MOTION * Increased release of EAA or ACh onto indirect pathway cells in striatum * Increased activation of indirect pathway neurons, leads to increased APs and GABA release onto GPe neurons * Increased GABA release onto GPe neurons leads to IPSP and Decreased AP and release of GABA from GPe onto the Subthalamic nuclei * Decreased GABA release onto subthalamic nuclei leads to depolarization and increased APs and release of EAA onto the SNPR/GPi * Increased release of EAA onto SNPR and GPi increases AP and release of GABA from these areas onto the thalamus * Increased release of GABA onto the thalamus leads to IPSP/Hyperpolarization and less EAA release from thalamus onto cortical neurons * End result: No motion